


Promise?

by SenpaiWikipedia



Category: Undertale
Genre: Depressed Sans, Depression, Implied/Referenced Child Abuse, Implied/Referenced Self-Harm, Just a simple not simple little lovey dovey story between two nerds, LIKE CRIPPLING SOCIAL ANXIETY SHY SANS, M/M, Might change rating/archive warnings later on, More tags to be added, Sans is obviously my favorite, Sans might have had a bad past, Sans' low HP is a problem, Shy Sans, Tall Gaster, Tiny Sans, which entitles him to get hurt/sick easily
Language: English
Status: In-Progress
Published: 2017-10-22
Updated: 2017-10-25
Packaged: 2019-01-21 03:50:48
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 3,860
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12449079
Author URL: https://archiveofourown.org/users/SenpaiWikipedia/pseuds/SenpaiWikipedia
Summary: W. D. Gaster, the underground's Royal Scientist, had been looking in to getting a new assistant, since his previous one had been promoted to a higher position. One of the new employees seems to catch his eye, and maybe later something else.Sans/W. D. Gaster fic :3





	1. Chapter 1

**Author's Note:**

> .....hi.

_Sigh_

Gaster filled his cup of coffee for the day, already tired and grumpy.

His assistant had been promoted. Yes, she deserved it, but now he was going to have to find a new one.

Perfect.

He looked over some files for a while, and thought maybe he would look through the employee's list for ideas on his assistant. 

His eyes scanned the list, that held their name, age, and one their accomplishements. His eyes fell on some pretty unique candidates, including someone who built a "self-sustaining tornado of trash, that will never cease to exist".

Gaster imagined what it would look like, chuckling at his thoughts.

Noticing his approaching hunger, he moved his chair and looked at the time.

Lunch.

Sighing, he went into the lab's cafeteria, and while they did not have the best food, it was fine.

While waiting in line to order food, he couldn't help but look at the practical sea of scientists all in one room.

Gaster usually ate in his office, however this time he took his meal to one of the newer employees sitting alone. He looked  very young, couldn't have been more than 20. Gaster was quite young himself, a mere 23. What really caught his attention, was the fact that the scientist was a skeleton, much like himself. 

"Hello, and good afternoon, my name is Dr. Gaster. Who are you?" He said politely. The skeleton had been looking into his phone, and hadn't seen Gaster, and when he spoke, the younger jumped.

"Oh. sorry, didn't see you there." He shyly responded."Am I in your way? Did you want to sit here?"

"No, I just wanted to sit with you, you seemed lonely, and I never get to connect with some of my employees." Gaster explained, looking at the shocked expression, on the smaller one.

"You're Dr. Gaster? I didn't know. Sorry. Oh! And I'm Sans. Uh...hi." He looked down. God, this was so embarrassing. He just embarrassed himself in front of the Royal Scientist. Any moment he'll be laughed a-

Gaster burst into laughter. And he couldn't stop either. He tried to maintain his cool, but whatever concentration he had, was gone.

And there it was. Sans could feel tears brimming his eyes. Oh god, they were starting to trail down his cheeks. 

"You were the one with the self-sustaining tornado of trash!" He chuckled,trying to calm down."I was looking through my notes this morning, and saw your 'accomplishment'".

Sans looked up at him. The tears seemed to stop at the scientists explanation.

"...Y-You're not laughing at m-me?" Sans quietly said, cringing at how pathetic he sounded.The doctor looked up at him with confusion in his eyes, then saw the tears.

"Hey why are you...wait. Oh, I'm so sorry, I-I didn't mean to make you cry! I'm sorry, I shouldn't have done that." Gaster grabbed a few of his napkins and gave them to his antsy employee. Sans took them graciously and wiped his eyes clean. Gaster felt really bad, and told him to wait right there. Sans watched as Gaster got up and went over to the dessert table, where he picked up a plate of strawberries and whip cream. 

"Here. I hope you can accept this as an apology. I do quite enjoy these, and I hope you do as well. Thank you for your time." He set the plate in front of Sans, who waited until Gaster was half way across the cafeteria to talk to more of his employees to start eating. His attention went back to his phone, and Gaster was right, these were good. Digging in to his 'apology dessert', he mind drifted to more important things.

\-----------

Gaster finally made it back into his office. One day. Just one day he wanted to go and socialize with his colleagues. And he made one of them cry.

Disaster. 

One of those people were going to have be his assistant, he had until the end of the week before his work would start to pile on him, requiring the help of a second person. None of them really possessed his ideal qualities for an assistant, and only one of the whatever amount of people he talked with, only one really caught his eye.

Staring deep into his reflection in his lukewarm coffee, he knew who he was gonna pick.


	2. Chapter 2

**Summary for the Chapter:**

> Sansy be getting his promotion woooo  
> and we meet a certain little not so little skele

Sans had since just dived into his work, not caring if he did it right. He just needed something to distract himself from today's earlier fiasco. He embarrassed himself in front of everyone, including his boss.

Sans groaned. He just wanted to sleep. It was only a few minutes until his shift was over, and he wanted out of here. 

As the seconds turned to minutes, one glance at the clock told him it was time to go. Before he could pack up, he felt a hand on his shoulder.

Not realizing there had been someone behind him, he girlishly let out a shriek.

"I have got to stop scaring you." A voice from behind said, chuckling.

"Dr. Gaster?", Sans questioned."What are you doing here? I-Isn't your office in the East Wing?" They were currently in the North Wing, where Sans' tiny substitute of an office was. Several testing rooms filled the gaps between Wings. There was an exit on the East and West sides, so that ruled out Gaster leaving.

"I'm here to congratulate you, Sans." He explained to the confused skeleton. "You're being promoted to my personal assistant, as I am need of one. I was in the cafeteria looking for possible candidants, and while our little chat hadn't had the best outcome, I saw something promising in you that could lead you to be an excellent assistant."

Sans paled. He was good at disappointing people, if that what Gaster meant by 'I saw something'. 

"U-Um...not to disrespect your choices and actions Dr. Gaster, but I feel as though you have picked the wrong monster. I don't think I could handle the responsibility, sir." Sans sheepishly said.

"You _think_ you can't handle the responsibility, but I _know_ you can. And please call me Gaster. Meet in my office at 8:40 on Monday, if you could, to discuss your new office arrangements. Have a good night." He turned to leave.

"...y-you too...." He quietly said, refusing to look up, until he knew Gaster was gone. He let out a sigh of relief, and went to pack his things. Well, at least he was coming home with good news.

\---------

Gaster had finished gathering all his paperwork, and headed home.'Home' wasn't much, just a decent apartment in Hotland. He couldn't even use the oven at all, a small layer of dust can be seen on the top. He was a horrible cook, and only ever heated things. With a microwave. Other than instant ramen noodles, he ordered pizza.

Walking in and closing the door, Gaster set down his bag on the couch. He opened the refrigerator and grabbed an apple. Turning on the TV, he bit into his apple, and thought about today's events.

He had succesly scared, flustered, sent to tears, and promoted one employee. In a little over 5 hours. If that was not impressive than Gaster didn't know what was. His new assistant had also requested to deny his promotion. That was a little strange. He did look adorable with that...flustered...expression.

Wait, did he think his new assistant was attractive? Geez, he was a sicko, a pervert, whatever you may. 

I'll just sleep on it, he decided. He must have been tired.

Getting into his sleepwear, he closed his eyes. He couldn't wait for Monday.

\----------

He couldn't go to work on Monday. He was just gonna embarrass himself once more. This was not helping his anxiety. The raise would be nice, but his social awkwardness wouldn't be very forgiving.

Finally reaching his house, he opened the door. It was pretty easy to tell apart his house from others. Unlocking the door and wiping his feet, he looked around. Kitchens not burned down, so he guessed his brother had not been cooking today. Speaking of his brother, you'd think, since they were twins, that they would be around the same height. But, nooooo. The universe had given him a curse worse than death. While his brother, Papyrus, is a little taller than most at 6"11, Sans was only 4"3. His lean and tiny body was so much different than his brother's big and bulky body. He needed a stepladder in order to do most of his chores.

"Papyrus? Are you home?" Sans called out, hoping to be given a response back.

"In my room!" A slightly muffled voice called back. Sans sighed and made his way up the stairs and towards his brother's room. He opened the knob, and saw Papyrus on his bed, reading one of his new comic books. 

"Got off training early?" Sans asked, sitting atop of his brother's bed, next to said brother.

"Yeah. Undyne tripped over one of her spears she forgot to dispel and banged up her knee. Won't have training for another 2 weeks. Gerson said she'll be alright though." Papyrus said, slightly bummed. "How was your day?"

"Um...a roller coaster." Sans stated, recalling his day again. "Was at lunch, checking stupid paperwork, when my boss just comes and casualty scares the crap out of me, then laughs at my face when I told him my name."

"That wasn't nice!" Papyrus exclaimed, making Sans flinch at the volume of his voice. "He apologized, right?"

"Yeah. Said sorry and all that stuff. Said he was going through list of workers that morning and recognized the beauty of my self-sustaining tornado of trash. Pretty sure that he liked it. But, uh...didn't do so well, _before_ the explanation. Embarrassed myself in front of my boss and my coworker by turning on the waterworks." He cringed, remembering the horror.

"Oh, Sans...it's alright, brother, I'm sure it wasn't that bad." Papyrus offered, trying to cheer up his brother. "In fact, why don't you cook tonight? Cooking always cheers you up a little."

"Ok." 

"Great, then! What are you going to cook?"

"Uh...maybe tacos?" Sans answered. He hadn't had tacos in a long time.

"Ok brother, I will set up the plates and silverware and after, I will be in my room. Call me when you are done!"

"K." Sans quickly made his way down the stairs. He opened the 'renovated sink', and pulled out his stepladder. The sink was to big for a stepladder so he had to climb on the sink and sit down in order to wash his hands. 

Unfortunately, his poor health was always taking a toll on him. Papyrus made sure to get Sans to wash his hands before and after any meal, or even before preparing one. One slip up could lead to him being bound to the bed for a few weeks, coughing up a lung.   

After cooking the meat, and slightly heating up the taco shells, he went to put on his and his brother's toppings. His was  just plain cheese and meat, while his brother had all different kinds of stuff on his.

"Papyrus! Dinners ready!" He called out, as loud as his naturally quiet voice would let him.

The thumping sounds of someone going down the stairs, told him his message was heard.

Sans smiles as he hands the plate to his much taller brother.

"I hope I got everything on it that you like, I haven't cooked in a while." said Sans, as he started to eat his taco, taking small, polite bites. Now his brother took a huge bite. And sauce now dropped down his chin. Sans giggled. Papyrus didn't care.

"Oh, I forgot to tell you something." Sans started. "After the crying incident, when I was just about to leave, Dr. Gaster came up to me again, and he decided to give me a promotion. Said he 'saw something in me'".

"Oh really? That's great brother! Where did you get moved to?" Papyrus asked, and Sans started GET anxious.

"H-He wanted me as his personal assistant, but I'm afraid I'll disappoint him.", he said meekly.

"Don't feel that way, brother. You just have to face your fears head on!" He encouraged.

"But that's not my thing, you can do that, I'm not sure I could." Sans sulked. "Guess I'll just have to deal with."

Papyus nearly cringed. "Almost there, Sans. Almost there."


	3. Chapter 3

**Summary for the Chapter:**

> .3.

**Notes for the Chapter:**

> Btw I'm going to try and update this everyday so you won't have to wait long :3

Sans sat in his bedroom, lit only by the light of his phone, Sunday night.He was currently playing a game where the goal, was just to feed a kawaii dog.(FEEDOG if you want to play it). Groaning, as he mistapped the dog and accidentally ate the chocolate, he turned off his phone and just stared at the ceiling.

He sighed. Life was hectic and unfair as always. Tommorow he would have to go in, and receive his promotion. Get his new office. Get a pay raise. But all that required the one thing he hated.

Socializing. Oh, how he dreaded the act. He would much rather drop dead and stop breathing. Attempting to control his thoughts, he plugged in his headphones to his phone and listened to music until sleep overcame him.

\------

_Beep! Beep! Beep!_

Gaster slammed a hand over the alarm, trying to find the snooze button. Finally waking up, he got dressed, and went to pour himself some coffee.

Leaving his apartment, he went down to path to the lab. Yawning he opened the doors, wishing any employee he encountered a good morning as he entered his office. He already had a stack of paperwork ready for his new assistant, and was ready to show Sans that he just be working down the hall. He needed his assistant nearby.

It was almost 8:40. Worried, he wondered if Sans wasn't going to come in. As if he was summoned, Sans, looking frantic and exhausted, burst open the door.

"I-I-I'm so sorry! I-I forgot t-to s-set my alarm l-last night! I slept i-in!" Sans stuttered. He was so worried. He had woken up very late, not having time to eat breakfast, as he ran half-way across the Underground to get to work in time.  (Btw Sans does not have his teleportation abilities yet).

"It's no worries. Do not fret, Sans, mistakes happen." He reassured. Sans let out a huge sigh of relief.

"U-Um...Dr. Gaster? D-Do you have a towel? The R-Riverperson wasn't there and I-I had to run through Waterfall." Sans asked. Upon looking, Gaster noticed Sans was soaking wet, part of his lab coat was dripping, and a slight blue haze was forming on his cheeks. The water and the humidity of Waterfall, closing with Hotland's scorching temperatures, can't be good for anyone.

"Oh dear, hold on...", Gaster said, "I think I've got something back here." Success! He fished a towel and a blanket out from under his desk. He went and took of his new assistant's lab coat, before wiping him down. After that, he let Sans sit down, with the blanket around his shoulders.

"Alright, I've got some paperwork for you to do for me, and I want to show you your new desk." Gaster explained, while Sans looked at the small stack of papers being handed to him. He looked them over, and decided he would do the builkiest part first, and work his way down. 

"Where i-is my new desk?" He tentatively asked. _Please be near a corner_ , he hoped. Life would be so much easier.

He was lead to a very nice looking desk, with a decent computer and everything. The desk itself was in a little spot outside Gaster's office. There was still a picture of the previous assistant and her family on the desk. Gaster took the picture and put it on the nearby shelf, to give it back to the former assistant.

Sans wiped his hands over the desk. Smooth polished wood greeted his senses. It smelled as though it had been cleaned recently. 

Gaster handed him the paperwork and Sans wasted no time to start on it. Gaster smiled at how determined Sans was to get this done.

"I will check in you before lunch to see your progress. Good luck, Sans." He turned around to go in his office, to get his own paperwork done.

It was about an hour away from lunch, when he heard a soft knock on his door. Gaster wondered who would be knocking.

"Come in." At those words, Sans pushed open the door, sweating a little, still wearing the blanket. Gaster couldn't hear all the small mumbles Sans was saying but it was something like "...doors....heavy". After composing himself, Sans gave him the stack of paperwork he had received this morning.

"You...finished?" Gaster questioned.

"Yep. I f-finished half an hour ago, but didn't want to play on my p-phone until you checked on me, you might have thought I-I was slacking,...so..." he looked away, flustered. He was rambling again.

"That's very impressive, especially someone your age. I know scientists older than me who can't finish that in a couple of hours." Gaster mused. Come to think of it, he doesn't know practically anything about his assistant. His old one was was quite the social butterfly, so it was a little awkward having someone who never talked about himself.

"Sans, would you care to eat your lunch with me? I hardly know you, and I want to learn a bit more about you." Gaster asked him. 

"Uh...ok, it's not like I have anything better to do.." he answered. 

\-----

Sans had excused himself before his little lunch chat to wash his hands. Looking at himself in the mirror of the bathroom he cleaned his face a little before walking back in to his boss' office.

Sans sat himself down, and silently began to eat his lunch.

"Now I just want to know the basics. If you want to go into depth on something, we can do that. Now just give me a quick summary of yourself." Gaster stated and took a bite out of his meal, waiting for a response.

"Uh...m-my name is Sans Serif, I'm 19(almost 20), I'm afraid of c-crowds and large a-animals, I live in in Snowdin...I like science, q-quantum physics/quantum mechanics and engineering in particular and m-music, and I have a twin brother. I-Is that enough?" Sans' mouth felt dry. That was basically his entire life, in only a few sentences. 

"Hmm...I get your fear of crowds, you're are quite the anti-socializer, but what led to your fear of large animals?" Gaster questioned. 

"W-With me being so small, I just don't feel comfortable knowing that t-they are the same size, if not b-bigger, than myself."

"Your brother...what's his name?"

"Papyrus. Funny s-story... he is nearly 3 feet taller than me. His best friends is Undyne, and he's training with her to become a royal g-guard." Sans let out a sigh of relief as Gaster announced, he would stop asking questions.

Sans politely excused himself, to wash his hands again.

This time, however, Gaster came with him. 

"Why do you wash your hands all the time?" Gaster asked him, curios.

"Weak immune system. I have l-lower HP than most, and I g-get sick easily." He answered.

Washing his hands throughly, he dried off any lingering water and went back to his office.

\-----

The day went by very fast, and when it was over, Sans walked home, a spring in his step. He couldn't wait to tell Papyrus about today. One thing he failed to notice, was the blanket from Gaster's office still wrapped around him, keeping him warm, as the night air blew around him.

 

 

 

 

 

 


	4. Chapter 4

**Summary for the Chapter:**

> Short chapter today sorry :(

**Notes for the Chapter:**

> Well he goes take three of TRYING TO TYPE THISGOT DELETED 2 TIMES

Sans opened the door to his home and was met with the sight of Papyrus and Undyne playing video games on the couch. Undyne's knee was wrapped up and carefully placed on top of a pillow, but that did not stop her from completely _crushing_ Papyrus in MarioKart.

"Hey guys." Sans said, startling the two bigger monsters. 

"Hey punk!" 

"Welcome home, brother!"

Sans put his lab coat on the coat hanger and took off his shoes.

Undyne won the race. 

No suprise there.

After the race she grabbed her crutches, and she made her to the kitchen, pouring herself some water. She was an aquatic monster, so she had to keep herself hydrated. 

"So how's work, nerd?" Undyne asked him.  

"Ok, I guess..." Sans answered.

"Brother! It is not just 'ok', you just got promoted! To the Royal Scientist's assistant, nonetheless! You should be ecstatic!" Papyrus exclaimed. Undyne looked confused about something after this was said.

"Wait, _you're_ the guy Gaster was talking about?" Undyne shouted. She had spit out her water saying this.

"You know Gaster?" Sans inquisitively asked. 

"Yeah. I have to check up on him to make sure work gets done and to make sure he'Ps alright. King's orders. But hey! He said he promoted a new assistant. Said you were the most anxious monster he had ever seen. Also the most adorable." She smirked.

Sans paled. He pulled the blanket to cover his face in an attempt to shy away from his brother and his friend.

Thats when it happened.

Papyrus and Undyne started laughing.

Sans couldn't take it. He ran up to his room, and his breathing got faster and faster, and then he was hyperventilating.

Papyrus and Undyne were still laughing, when they heard the door shut loudly.

Papyrus realized what happened, and immediately went upstairs. Undyne came with him, but she needed help with getting upstairs.

When they finally got to Sans' door, Papyrus knocked on the door, lightly.

"..." There was no answer. 

"Sans? Will you come out, please?"

After finding out the door had already been locked, Papyrus asked again.

This time, light footsteps were heard before a click! sounded, and the two were met with a teary-eyed, scared looking Sans. 

"Hey, what's wrong?" Papyrus asked, crouching down to Sans' level. 

Sans gave a weary look towards Undyne, and quickly back to the ground. Papyrus understood the gesture, and asked Undyne to leave them alone for a few minutes.

After the door closed, Papyrus gave a sympathetic look towards his brother. Sans locked him in an embrace, and let silent tears fall. Papyrus once again asked what was wrong.

"I-I j-just don't like t-to b-b l-l-laughed at." He said, shaking. It was like the Gaster situation all over again.

"Hey it's alright. We won't do it again, and I'll be _sure_ to tell Undyne to tone it back." Papyrus comforted.

"Can we let her in now?" Papyrus asked, calm and Sans nodded. Papyrus opened the door and beckoned Undyne inside. She was immediately met with a hug by the smaller skeleton. She smiled and rubbed circles on his back. He finally let go of her, and they went back downstairs. Undyne wished them goodbyes she left for her home back in Waterfall.

Sans said goodnight to his brother, and went to bed, the blanket covering his small frame.

**Author's Note:**

> ....bye.
> 
> Sorry so short, will DEFINETLY EXTEND THIS


End file.
